Metal-polymer pairs, factors

Factors Influencini the Priction in Metal—Polymer Pairs... 

The nature of the metal counterhody significantly influences the wear of contacting polymers (Table 4.11). Under low loads and friction velocities tribological characteristics of metal-polymer friction pairs depend only slightly on the metal nature. As soon as the load-velocity regime becomes more severe, the role of this factor increses drastically [108]. 

Fig. 4.21. Functional interrelation of the factors promoting mechanochemical wear of the metal-polymer friction pair...

The analysis of corrosion factors during polymer-metal pair wear has proved that the main path is electrochemical protection of the metal counterbody neutralization of corrosion agents formed in the friction zone and suppression of corrosion processes in the polymer-metal contact. These directions are realized by the means illustrated in Fig. 4.6 [37]. They are subdivided into two groups according to the use of special substances or physical fields and power effects. 

Commercial polypropylene is based on catalysts of the Ziegler-Natta type that produce a product with an isotactic content of 90 percent or more. The presence of the methyl groups restricts movement of the polymer molecules somewhat, and crystallization rarely exceeds 65 to 70 percent. The degree of stereoregularity depends on a multitude of factors, some of which are not well understood. Variables include the type of metals in the catalyst, their oxidation states and crystal structure, and the organic functionality in the complex. In some systems both the rate of reaction and the degree of stereoregularity are increased by the addition of electron pair donors such as amines. 

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